Engineers at Japan's Fukushima nuclear plant are preparing to extract the first of thousands of fuel rods from the wrecked reactor-four building. This delicate task is a major step on the long road to making the site safe, reports the BBC's Rupert Wingfield-Hayes.

If you open an Internet search engine and type in "Fukushima reactor four" you may be forgiven for thinking the world is about to end.

There are some pretty scary stories circulating about what is about to happen at the plant.

Some predict a disaster that will make Tokyo uninhabitable - others go further. Why? It comes down to what is, in the next few weeks, going to start happening inside one building at the destroyed nuclear plant.

There is a very good reason why the outside world is obsessed with the reactor-four building - the enormous amount of radioactive material it contains.

Removing fuel rods

The fuel rods - 4m-long tubes containing pellets of uranium fuel - are in a precarious state in the Unit Four storage pool

The rod assemblies will be lifted out in batches of 22 in casks filled with water, using a crane - each batch will take 7-10 days

Two critical issues are whether the rods were damaged during the disaster and so are likely to leak, and whether the casks remain watertight so the rods have no contact with air

The fuel rods will be deposited into a new "common" pool with a cooling system

On the Internet, measures including three Chernobyls and 14,000 Hiroshimas are used to describe the volume of radioactive material. Suffice to say that it is a lot - nearly 500 tonnes of nuclear fuel, around 100,000 fuel rods.

On Thursday I was one of a small number of journalists allowed inside reactor building four for the first time since the disaster. These trips are gruelling. Hours are spent on buses, in waiting rooms, being lectured, all for a few minutes looking in to a dark green pool.

So what can I report? Mainly that I feel somewhat reassured by what I have seen. The preparations for the fuel removal appear meticulous.

Over the past year a massive new structure has been built over the building to carry the huge cranes that will lift the fuel.

The fuel pool has been cleaned - even using an underwater vacuum to remove debris from the 2011 explosions. Looking down into the pool today the water was clear, the fuel assemblies clearly visible.

Image caption
Removing the fuel rods will be a long and painstaking process

That does not mean there will not be problems. Some of the assemblies could be cracked or damaged. Even if everything goes to plan, it will take at least a year to remove all the fuel.

But there is a plan, and according to Japanese and foreign experts I have spoken to, it is achievable. None of them told me they fear an apocalypse.

Dead zone

But visiting the plant, it struck me that in our obsession with reactor four we may be missing the real story at Fukushima.

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Thousands of fuel rods need to be removed and stored

I have recently received a new sophisticated radiation monitor sent from London, which has now had its first outing in the field. You can point it at things and it tells you how many "counts per second" of radiation the object is giving off.

Inside reactor building four the readings were constantly low - not surprising when you remember that reactor four had no meltdown. The reactor was offline when the tsunami struck. That is not true with reactors one, two and three.

As our bus left reactor four and drove along the sea front, I pointed my new monitor out of the window towards reactor building three. Suddenly the needle started to spike - 1,000 counts per second, then 2,000, 3,000, finally it went off the scale.

There, outside the bus, just a few dozen meters away is the real dead zone, a place where it is still far too dangerous for anyone to go. No human has been inside reactor three since the disaster. To do so would be suicide. No-one knows when it will be possible to go in.

When I asked the same experts how long it would be until reactors one, two and three could be dismantled, they shook their heads. When I asked them where they thought the melted reactor cores were, they shook their heads again.

Tokyo Electric Power Company was happy to show us reactor four, but please do not ask what they intend to do with reactors one, two and three.